Protector for electric circuits

ABSTRACT

The fragile fusible element of a low amperage electric fuse is protected by being mounted adjacent a longitudinally extending central opening within a support and by being made so it is undulatory in configuration.

United States Patent 1111 3,568,122

[72] Inventor Angelo Urani [56] References Cited Louis, UNITED STATESPATENTS m1 APPLNQ 8644572 2,727,109 12/1955 VonHoorn 337/166 [221 PM2,828,390 3/1958 McAlister 337/232 [45] Patented Mar.2, 1971 3,246,1054/1966 Uram 337/183 [73] Assrgnee McGraw-Edlson Company E| i PrimaryExaminer-G. Harris [54] PROTECTOR FOR ELECTRIC CIRCUITS AssistantExaminer-F. E. Bell Attorney-Kingsland, Rogers, Ezell, Eilers & RobbinsABSTRACT: The fragile fusible element of a low amperage electric fuse isprotected by being mounted adjacent a longitudinally extending centralopening within a support and by being made so it is undulatory inconfiguration.

PROTECTOR FOR ELECTRIC CIRCUITS This invention relates to improvementsin Protectors For Electric Circuits. More particularly, this inventionrelates to improvements in low amperage electric fuses.

It is, therefore, an object of the present invention to provide animproved low amperage electric fuse.

The fusible elements that are used in low amperage electric fuses havesuch small diameters that those fusible elements tend to be quitefragile. As a result, those fusible elements should be protected againstinjury during the manufacture, shipment and use of the low amperageelectric fuses of which they are component parts. The fusible element ofthe present invention is protected against injury, during themanufacture, shipment and use of the low amperage electric fuse of whichit is a component part, by being mounted adjacent a longitudinallyextending central opening within a support and by being made so it isundulatory in configuration. The portions of that support which define,and which extend outwardly from, that central opening tend to protectthat fusible element by holding objects away from the sides of thatfusible element; and the undulatory configuration of that fusibleelement tends to protect that fusible element by permitting that fusibleelement to yield if any object engages the top of that fusible element.As a result, the fusible element of the present invention is resistantto injury,.during the manufacture, shipment and use of the low amperageelectric fuse of which it is a component part. It is, therefore, anobject of the present invention to provide a low amperage electric fusewhich has the fusible element thereof of undulatory configuration andmounted adjacent a longitudinally extending central opening within asupport.

Because the fusible elements of low amperage electric fuses have verysmall diameters, the unit-lengthresistances of those fusible elementsare relatively high; and hence it is important to fix the effectivelengths of those fusible elements. The present invention fixes theeffective length of the fusible element of the low amperage electricfuse thereof by forming precisely spaced contact areas at the ends ofthe longitudinally extending opening in the support for that fusibleelement and by forming notches in the ends of that support to fix thepositions of the ends of that fusible element relative to those contactareas. The sides of the notches in the ends of the support for thefusible element are inclined relative to each other to make thosenotches generally V-shaped in configuration; and

those notches enable moderate forces, applied to the ends of the fusibleelement, to guide those ends into predetermined positions relative tothe contact areas on that support. The use of such moderate forces isimportant, because such forces will not stretch or distort the fusibleelement. The overall result is that the effective length of the fusibleelement of the low amperage electric fuse of the present invention canbe easily and accurately fixed. It is, therefore, an object of thepresent invention to provide a support, for the fusible element of anelectric fuse, which has precisely shaped contact areas. at the ends ofa longitudinally extending opening therein and which has generallyV-shaped notches in the ends thereof to enable moderate fuses to guidethe ends of that fusible element into predetermined positions relativeto those contact areas.

Other and further objects and advantages of the present invention shouldbecome apparent from an examination of the drawing and accompanyingdescription.

In the drawing and accompanying description two preferred embodiments ofthe present invention are shown and described but it is to be understoodthat the drawing and accompanying description are for the purpose ofillustration only and do not limit the invention and that the inventionwill be defined by the appended claims.

In the drawing, FIG. 1 is an enlarged, longitudinal, sectional viewthrough one preferred embodiment of low amperage electric fuse that ismade in accordance with the principles and teachings of the presentinvention;

FIG. 2 is an enlarged, longitudinal, sectional view which is similar tothat of FIG. 1 but wherein the electric fuse has been rotated about thelongitudinally extending axis thereof:

FIG. 3 is a sectional view, on a still large scale, through the electricfuse of FIG. 1, and it is taken along the plane indicated by the lines3-3 in FIG. 1;

FIG. 4 is a sectional view, on the scale of FIG. 3, through the electricfuse of FIG. 1, and it is taken along the plane indicated by the line 44in FIG. 3;

FIG. 5 is a perspective view of a second preferred embodiment of lowamperage electric fuse that is made in accordance with the principlesand teachings of the present invention;

FIG. 6 is a broken-away, elevational view of an electromagnetic coil inwhich the electric fuse of FIG. 5 is embedded;

FIG. 7 is a sectional view, on a larger scale, through the electric fuseof FIG. 5, and it is taken along the plane indicated by the line 77 inFIG. 6; and

FIG. 8 is a sectional view which is similar to that shown in FIG. 7 butwherein part of the insulation for the electromagnetic coil has engagedand moved part of-the fusible element.

Referring to the drawing in detail, the numeral 20 denotes a supportwhich is made from an insulating material which can withstand thetemperatures used in soldering, which can have an opening and notchesformed therein by a punching operation, and which is dimensionallystable. While different materials could be used in making the support20, phenolic resins have been found to be very useful. The numeral 22denotes a longitudinally directed, rectangular opening in the support20, As emphasized by FIGS. 1 and 2, that opening is spaced inwardly fromeach side of the support 20, and also is spaced inwardly from each endof that support. In actual practice, the geometric center of the opening22 is coincident with the geometric center of the support 20. Thenumeral 24 denotes the V-shaped entrance of an aligning notch 26 in theleft-hand end of the support 20; and the geometric centers of the notchand of that V-shaped entrance lie on the longitudinally directed centerline of that support. The numeral 28 denotes the V-shaped entrance of analigning notch 30 in the right-hand end of the support 20; and thegeometric centers of that notch and of that V-shaped entrance lie on thel0ngitudinally directed center line of that support.

The numeral 32 denotes a contact area which overlies the upper surfaceof the left-hand end of the support 20; and that contact area is madefrom a metal with which solder can readily alloy. The right-hand edge ofthe contact area 32 terminates adjacent the left-hand end of the opening22 in the support 20. The numeral 34 denotes a contact area whichoverlies the upper surface of the right-hand end of the support 20; andthat contact area is made from a metal with which solder can readilyalloy. The left-hand edge of the contact area 34 terminates adjacent theright-hand end of the opening 22. Because the opening 22 will preferablybe formed by a punching operation, and thus may have minute burrs orprojections at the ends thereof, the confronting edges of the contactareas 32 and 34 are spaced outwardly from the ends of the opening 22.The V- shaped entrances 24 and 28 and the notches 26 and 30 also willpreferably be formed by a punching operation; and in actual practice,the opening 22, the V-shaped entrances 24 and 28, and the notches 26 and30 are all punched at the same time.

The numeral 36 denotes a wirelike fusible element of small diameter; andthat diameter will vary with the ampere rating of the electric fuse.However, in all cases, the diameter of that fusible element will be verymuch smaller than that shown in FIGS. 1-4. The numeral 38 denotes aportion of the fusible element 36 which has been bent downwardly throughthe notch 26 and then bent into engagement with the bottom surface ofthe support 20. The numeral 40 denotes a portion of the fusible element36 which has been bent downwardly through the notch 30 and then bentinto engagement with the support 20. The fusible element 36 has a seriesof reverse bends therein; and those bends provide an undulatoryconfiguration for that fusible element.

Where the electric fuse provided by the present invention is to beassembled by hand, the V-shaped entrances 24 and 28 and the notches 26and 30 will enable the assembler to use only moderate forces in guidingthe ends of the fusible element 36 into registry with the longitudinallydirected center line of the support 20. The use of moderate forces isimportant, because such forces will not stretch or distort that fusibleelement. The V-shaped entrances 24 and 28' and the notches 26 and 30will, after the portions 38 and 40 of the fusible element 36 have beenbent downwardly through the notches 26 and 30 and then into engagementwith the bottom surface of the support 20, help hold that fusibleelement in registry with the longitudinally directed center line of thatsupport. Where the electric fuse provided by the present invention is tobe assembled by a machine, the V-shaped entrances 24 and 28 and thenotches 26 and'30 again will enable moderate forces to be used inguiding the ends of the fusible element 36 into registry with thelongitudinally directed center line of the support 20. The V-shapedentrances 24 and 28 and the notches 26 and 30 will, after the portions38 and 40 of the fusible element 36 have been bent downwardly throughthe notches 26 and 30 and then into engagement with the bottom surfaceof the support 20, help hold that fusible element in registry with thelongitudinally directed center line of that support.

The contact area 32 and the contact area 34 can be made in differentways. One preferred way of making those contact areas is to form spacedlayers of copper on the upper surface of the support 20, and then formcoatings of tin on those spaced layers of copper. When made in that way,the contact areas 32 and 34 will have upper surfaces with which soldercan readily alloy.

The numeral 42 denotes solder which bonds the left-hand end of thefusible element 36 to the contact area 32 and the numeral 43 denotessolder which bonds the right-hand end of that fusible element to thecontact area 34. The solder 42 and 43 will not only electrically bond,but also will mechanically secure, the fusible element 36 to the contactareas 32 and 34.

The numeral 46 denotes a wirelike connecting element which is made froma metal having a low resistivity and a relatively high degree ofductility. The inner end of the connecting element 46 overlies a portionof the contact area 32 and is electrically bonded, and mechanicallysecured, to that contact area by solder 48. The numeral 50 denotes awirelike connecting element which is similar to the connecting element46. The inner end of the connecting element 50 overlies a portion of thecontact area 34 and is electrically bonded, and mechanically secured, tothat contact area 34 by solder 52. While the connecting elements 46 and50 could be made of different metals, copper has been found to be veryuseful.

While the solder 42 is shown as being separate and discrete from thesolder 48, the solder 48 merges with and becomes almostindistinguishable from the solder 42. Similarly, while the solder 43 isshown as being separate and discrete from the solder 52, the solder 52merges with and becomes almost indistinguishable from the solder 43. Inapplying the solder 42 and the solder 48 to the contact area 32, thesource of heat for the soldering operation will be spaced from theleft-hand end of the fusible element 36 so that source of heat will notinterfere with the positioning of that fusible element in register withthe longitudinally directed center line of the support 20. Similarly, inapplying the solder 43 and the solder 52 to the contact area 34, thesource of heat for the soldering operation will be spaced from theright-hand end of the fusible element 36 so that source of heat will notinterfere with the positioning of that fusible element in register withthe longitudinally directed center line of the support 20.

The numeral 54 denotes a tubular casing of insulating material for theelectric fuse of the present invention; and the inner diameter of thatcasing is large enough to permit the support 20 to be telescoped freelywithin thatcasing. As shown by FIGS. 1 and 2, the casing 54 isconsiderably longer than the support 20; and that support has the endsthereof spaced inwardly from the opposite ends of that casing. While thecasing a 54 can be made of different materials, glass has been found tobe very useful.

The outer end of the connecting element 46 is bent around the left-handend of the casing 54, and then is bent into engagement with a portion ofthe outer surface of that casing. Similarly, the outer end of theconnecting element 50 is bent around the right-hand end of the casing54, and then is bent into engagement with a portion of the outer surfaceof that casing. The numeral 56 denotes a ferrulelike terminal; and theinner diameter of that terminal is large enough to enable that terminalto be telescoped over the left-hand end of the casing -54 and over thebent outer end of the connecting element 46.

The numeral 58 denotes a mass of solder which electrically bonds theconnecting element 46 to the terminal 56.

The numeral 62 denotes a ferrulelike terminal which is similar to theferrulelike terminal 56. The inner diameter of the terminal 62 is largeenough to enable that terminal to be telescoped over the right-hand endof the casing 54 and over the bent outer end of the connecting element50. The numeral 64 denotes a mass of solder which electrically bonds theconnecting element 50 to the terminal 62.

In fabricating the electric fuse provided by .the present invention, thecontact areas 32 and 34 are formed on the opposite ends of the uppersurface of the support 20. Thereafter, the opening 22, the V-shapedentrances 24 and 28, and the notches 26 and 30 are formed by a punchingoperation. While the punch and die that are used in forming the opening22, the V-shaped entrances 24 and 28, and the notches 26 and 30 will bedesigned to leave the ends of the opening 22 as free from burrs andrough sports as possible, some burrs and some rough spots will be formedat those ends. However, those burrs and rough spots will have heightsless than the thicknesses of the contact areas 32 and 34; and hencethose contact areas will space the portions of the fusible element 36,which are in register with the ends of the opening 22, away from thoseends. This means that burrs and rough spots on the ends of the opening22 will be unable to cut or otherwise impair the fusible element 36 asthat fusible element is assembled with the support 20. At the time theopening 22, the V-shaped entrances 24 and 28, and the notches 26 and 30are punched, or at some subsequent time, the ampere rating of theelectric fuse will be stamped into the bottom surface of the support 20.In the preferred embodiment of electric fuse shown by FIGS. 1-4, theampere rating is 1 A, and hence a l and a /4 are stamped into the bottomsurface of the support 20.

In assembling the fusible element 36 with the support 20, that fusibleelement will be gripped by the assembler, or by the machine which isused in fabricating the electric fuse; and then the ends of that fusible1 element will be moved downwardly toward the support 20. The V-shapedentrances 24 and 28 will automatically guide the ends of the fusibleelement 36 into register with the notches 26 and 30, and hence willautomatically guide that fusible element into position wherein it isgenerally parallel to the longitudinally directed center line of thatsupport. The curved inner ends of the notches 26 and 30 will help guidethe ends of the fusible element 36 into registry with thatlongitudinally directed center line; and then the assembler, or themachine which is used in fabricating the electric fuse, will bend theends of that fusible element downwardly through the notches 26 and 30into engagement with the bottom surface of the support 20. Once the endsof the fusible element 36 have been bent into engagement with thatbottom surface, any excess lengths of those ends can be cut away; and,thereafter, no further handling of the fusible element 36 will berequired. This is desirable, because it minimizes the risk of breakingor fatiguing that small diameter, inherently fragile, fusible element.

The connecting elements 46 and 50 will then be disposed so theconfronting ends thereof overlie the contact areas 32 and 34; and thenthe solder 42, 43, 48 and 52 will be applied to those contact areas toelectrically bond, and mechanically secure, those connecting elementsand the fusible element 36 to those contact areas. The solder 42 willflow up to, but will stop at, the right-hand edge of the contact area32; and the solder 43 will flow up to, but will stop at, theleft-handedge of the contact area 34. Theportion of the fusible element36 which is disposed between the confronting edges of the contact areas32 and 34 is the effective length of that fusible element; and thateffective length will be fixed by the precise spacing between theconfronting edges of the contact areas 32 and 34 and by the positioningof that fusible element so it is generally parallel to thelongitudinally directed center line of the support 20.

Referring particularly to FIGS. 5 8, the numeral 70 generally denotes asecond embodiment of electric fuse that is made in accordance with theprinciples and teachings of the present invention. That secondembodiment can be identical with the embodiment shown in FIGS. 1-4,except for the fact that it isnot enclosed within a casing such as thecasing 54. In

stead,-the electric fuse 70 will be directly embedded within an of turnsthereof; .and two of those layers are denoted by the numerals 74 and 76.In addition, the coil 72 has an outer layer 78 of insulation. While thelayers 74, 76 and 78 of insulation are shown by FIGS. 7 and 8 as beingspaced apart, those layers will usuallybe parts of one continuous stripof insulation. The connecting elements 46 and 50 .of the electric fuse70 of FlGS.5-8 are connected to portions of the terminal 80 of the coil72, and thus are connected in series with that terminal, with the coil72, and with the terminal 82. in the event that coil is subjected to apotentially hurtful overload, the fusible element 36 will fuse andthereby prevent an electrical fire.

As shown by FIGS. 7 and 8, the bottom surface of the support will bedisposed against the layer 76, and then the outer layer 78 will beplaced adjacent the upper surface of that support. That outer layer maybear against the upper surface of the fusible element 36, but thereverse bends in that fusible element will space many portions of thatfusible element away from that outer layer. This is desirable; becauseit will keep the outer layer 78 from absorbing undue amounts of heatfrom those portions of the fusible element 36.

The portions of the support 20 which define, and which extend outwardlyfrom, the central opening 22 will tend to protect the fusible element 36by holding objects away from the sides of that fusible element. As aresult, the sides of that fusible element are protected from injurywhile the electric fuse 70 is being manufactured, shipped and used.Because the fusible element 36 is undulatory in configuration, andbecause the effective length thereof is in register with the opening 22,that fusible element will be able to yield, rather than break, when aforce is applied to the top thereof. Thus, as indicated by FIGS. 7 and8, the fusible element 36 can respond to a force, which dents the outerlayer 78, to move further into the opening 22 rather than to break. Theoverall result is that the electric fuse 70 of FIGS. 5-8 can safely beused as an open fuse, and can be embedded within the winding of anelectromagnetic coil.

Whereas the drawing and accompanying description have shown anddescribed two preferred embodiments of the present invention it shouldbe apparent to those skilled in the art that various changes may be madein the form of the fuse without affecting the scope thereof.

I claim:

1. An electric fuse that comprises:

an insulating support which has an opening therein and which hasaligning notches therein;

contact areas on said insulating support intermediate said opening andsaid aligning notches;

said contact areas being spaced apart by said opening;

a fusible element that spans said opening and that has the ends thereofoverlying said contact areas and extending into said alignment notches;

solder electrically bonding, and mechanically securing, said ends ofsaid fusible element to said contact areas; and

said fusible element having reverse bends therein which givesaid'fusible element an undulatory configuration.

2. An electric fuse as claimed in claim 1 wherein the confronting edgesof said contact areas are spaced outwardly of the adjacent edges of saidopening, and thus are spaced outwardly of any burrs and rough spots onsaid adjacent edges of said opening.

3. An electric fuse as claimed in claim 1 wherein said opening isdisposed inwardly of all portions of the periphery of said insulatingsupport, and wherein said portions of the periphery of said insulatingsupport protect said fusible element by hold ing all objects away fromthe sides of said fusible element.

4. An electric fuse as claimed in claim 1 wherein some of said reversebends in said fusible element are disposed within said opening, andwherein said opening and the reverse bends in said fusible element coactto enable said fusible element to move inwardly of said opening, ratherthan to break, in response to the application of a force to the top ofsaid fusible element.

5. An electric fuse as claimed in claim 1 wherein said opening isrectangular in configuration and wherein said fusible element isparallel to the long axis of said opening.

6. An electric fuse as claimed in claim 1 wherein said aligning notcheshave generally V-shaped entrances and arcuate inner ends.

7. An electric fuse as claimed in claim 1 wherein said ends of saidfusible element are bent downwardly to extend through said aligningnotches and are then bent to engage the bottom surface of saidinsulating support.

8. An electric fuse that comprises:

an insulating support which has an opening therein and which hasportions that define and that extend outwardly from said opening; Icontact areas on said insulating support intermediate said opening andthe periphery of said insulating support;

said contact areas being spaced apart by said opening;

a fusible element that spans said opening and that has portions thereofoverlying said contact areas;

solder electrically bonding, and mechanically securing, said portions ofsaid fusible element to said contact areas;

said fusible element having reverse bends therein which give saidfusible element an undulatory configuration;

said portions of said insulating support that define and that extendoutwardly from said opening protecting said fusible element by spacingobjects away from the sides of said fusible element; and

said opening in said support and said undulatory configuration of saidfusible element enabling said fusible element to respond to a forceapplied to the top of said fusible element to move into said openingrather than to break.

9. An electric fuse as claimed in claim 8 wherein the confronting edgesof said contact areas are spaced outwardly of the adjacent edges of saidopening, and thus are spaced outwardly of any burrs and rough spots onsaid adjacent edges of said opening.

10. An electric fuse as claimed in claim 8 wherein some of said reversebends in said fusible element are disposed within said opening andwherein other of said reverse bends are disposed above said opening.

11. An electric fuse as claimed in claim 8 wherein said contact areasspace said portions of said fusible element above the upper surface ofsaid insulating support and thereby space said portions of said fusibleelement above burrs and rough spots on the adjacent edges of saidopening.

12. An electric fuse as claimed in claim 8 wherein said opening isrectangular in configuration and wherein said fusible element isparallel to the long axis of said opening.

13. An electric fuse as claimed in claim 8 wherein connecting elementshave the inner ends thereof overlying, and electrically bonded andmechanically secured to, said contact areas, and wherein said connectingelements have the outer ends thereof extending outwardly from and beyondsaid contact areas.

14. An electric fuse that comprises:

an insulating support which has an elongated, centrally located openingtherein and which has aligning notches in the ends thereof;

contact areas on said support intermediate the ends of said centrallylocated opening and said aligning notches;

said contact areas being spaced apart by said centrally located opening;

a fusible element that spans said centrally located opening and that hasthe ends thereof overlying said contact areas and extending into saidalignment notches and bent under the bottom surface of said insulatingsupport;

connecting elements having'the inner ends thereof overlying said contactareas and having the outer ends thereof extending outwardly beyond saidends of said support;

solder electrically bonding and mechanically securing said ends of saidfusible element and said inner ends of said connecting elements to saidcontact areas;

said alignment notches defining a line which extends longitudinally ofsaid support and of said centrally located opening; and

said fusible element having reverse bends therein to give said fusibleelement an undulatoryiconfiguration.

15. The method of making a support-type fuse which comprises forming athin fusible element so it has an undulatory configuration, forming asupport so it has an opening therein and so it has generally V-shapednotches in the ends thereof and so it has contact areas on said endsthereof, moving said fusible element into register with aline betweensaid generally V-shaped notches, moving the ends of said fusible elementdownwardly into said generally V-shaped notches to move a portion ofsaid fusible element into register with said opening in said support andto move further portions of said fusible element into engagement withsaid contact areas, said generally V-shaped notches enabling the firstsaid portion of said fusible element to be moved into register with.said opening and enabling said further portions of said fusible elementto be moved into engagement with said contact areas withoutnecessitating the use of forces which could elongate or distort saidfusible element, and electrically bonding and mechanically securing theends of said fusible element to said contact areas.

1. An electric fuse that comprises: an insulating support which has anopening therein and which has aligning notches therein; contact areas onsaid insulating support intermediate said opening and said aligningnotches; said contact areas being spaced apart by said opening; afusible element that spans said opening and that has the ends thereofoverlying said contact areas and extending into said alignment notches;solder electrically bonding, and mechanically securing, said ends ofsaid fusible element to said contact areas; and said fusible elementhaving reverse bends therein which give said fusible element anundulatory configuration.
 2. An electric fuse as claimed in claim 1wherein the confronting edges of said contact areas are spaced outwardlyof the adjacent edges of said opening, and thus are spaced outwardly ofany burrs and rough spots on said adjacent edges of said opening.
 3. Anelectric fuse as claimed in claim 1 wherein said opening is disposedinwardly of all portions of the periphery of said insulating support,and wherein said portions of the periphery of said insulating supportprotect said fusible element by holding all objects away from the sidesof said fusible element.
 4. An electric fuse as claimed in claim 1wherein some of said reverse bends in said fusible element are disposedwithin said opening, and wherein said opening and the reverse bends insaid fusible element coact to enable said fusible element to moveinwardly of said opening, rather than to break, in response to theapplication of a force to the top of said fusible element.
 5. Anelectric fuse as claimed in claim 1 wherein said opening is rectangularin configuration and wherein said fusible element is parallel to thelong axis of said opening.
 6. An electric fuse as claimed in claim 1wherein said aligning notches have generally V-shaped entrances andarcuate inner ends.
 7. An electric fuse as claimed in claim 1 whereinsaid ends of said fusible element are bent downwardly to extend throughsaid aligning notches and are then bent to engage the bottom surface ofsaid insulating support.
 8. An electric fuse that comprises: aninsulating support which has an opening therein and which has portionsthat define and that extend outwardly from said opening; contact areason said insulating suppOrt intermediate said opening and the peripheryof said insulating support; said contact areas being spaced apart bysaid opening; a fusible element that spans said opening and that hasportions thereof overlying said contact areas; solder electricallybonding, and mechanically securing, said portions of said fusibleelement to said contact areas; said fusible element having reverse bendstherein which give said fusible element an undulatory configuration;said portions of said insulating support that define and that extendoutwardly from said opening protecting said fusible element by spacingobjects away from the sides of said fusible element; and said opening insaid support and said undulatory configuration of said fusible elementenabling said fusible element to respond to a force applied to the topof said fusible element to move into said opening rather than to break.9. An electric fuse as claimed in claim 8 wherein the confronting edgesof said contact areas are spaced outwardly of the adjacent edges of saidopening, and thus are spaced outwardly of any burrs and rough spots onsaid adjacent edges of said opening.
 10. An electric fuse as claimed inclaim 8 wherein some of said reverse bends in said fusible element aredisposed within said opening and wherein other of said reverse bends aredisposed above said opening.
 11. An electric fuse as claimed in claim 8wherein said contact areas space said portions of said fusible elementabove the upper surface of said insulating support and thereby spacesaid portions of said fusible element above burrs and rough spots on theadjacent edges of said opening.
 12. An electric fuse as claimed in claim8 wherein said opening is rectangular in configuration and wherein saidfusible element is parallel to the long axis of said opening.
 13. Anelectric fuse as claimed in claim 8 wherein connecting elements have theinner ends thereof overlying, and electrically bonded and mechanicallysecured to, said contact areas, and wherein said connecting elementshave the outer ends thereof extending outwardly from and beyond saidcontact areas.
 14. An electric fuse that comprises: an insulatingsupport which has an elongated, centrally located opening therein andwhich has aligning notches in the ends thereof; contact areas on saidsupport intermediate the ends of said centrally located opening and saidaligning notches; said contact areas being spaced apart by saidcentrally located opening; a fusible element that spans said centrallylocated opening and that has the ends thereof overlying said contactareas and extending into said alignment notches and bent under thebottom surface of said insulating support; connecting elements havingthe inner ends thereof overlying said contact areas and having the outerends thereof extending outwardly beyond said ends of said support;solder electrically bonding and mechanically securing said ends of saidfusible element and said inner ends of said connecting elements to saidcontact areas; said alignment notches defining a line which extendslongitudinally of said support and of said centrally located opening;and said fusible element having reverse bends therein to give saidfusible element an undulatory configuration.
 15. The method of making asupport-type fuse which comprises forming a thin fusible element so ithas an undulatory configuration, forming a support so it has an openingtherein and so it has generally V-shaped notches in the ends thereof andso it has contact areas on said ends thereof, moving said fusibleelement into register with a line between said generally V-shapednotches, moving the ends of said fusible element downwardly into saidgenerally V-shaped notches to move a portion of said fusible elementinto register with said opening in said support and to move furtherportions of said fusible element into engagement with said contactareas, said generally V-shaped notches enabling the fIrst said portionof said fusible element to be moved into register with said opening andenabling said further portions of said fusible element to be moved intoengagement with said contact areas without necessitating the use offorces which could elongate or distort said fusible element, andelectrically bonding and mechanically securing the ends of said fusibleelement to said contact areas.